Air-engine



0. M. STILLMAN AIR ENGINE.

Patented June 26, 1860.

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UNITED STATES PATENT orricn.

O. M. STILLMAN, OF YS'IOINGTON, CONNECTICUT.

AIR-ENGINE.

Specification of Letters Patent No. 28,910, dated June 26, 1860.

T o all whom it may concern:

Be it known that I, O. H. STILLMAN, of Stonington, in the county of NewLondon and State of Connecticut, have invented certain new and.. usefulImprovements in Air-Engines, whereby they are simplified in constructionand rendered more efficient; and I do hereby declare that the following`is a full, clear, and exact description of the same, reference beinghad to the accompanying drawing, which is a vertical section of anengine containing my improvements.

The nature of my invention consists in a means of compressing andworking the air in a single cylinder by the use of but one piston. Alsoin combining the stuflingbox with the induction valve in such a mannerthat the friction of the former upon the piston rod controls and aidsthe operation of the latter, preventing it from slamming and aiding itto open and close at the proper periods. Also, in a means of cooling theinterior of the piston and piston rod. Also,

in a means of cooling the exterior of the cylinder.

To enable others skilled in the art to make and use my invention, I willproceed to describe its construction and operation by the aid of thedrawing and of the letters of reference marked thereon.

A is a hollow cylinder with heads A', A.

B is a piston fitted therein having a large hollow piston-rod B cast inthe same piece or otherwise attached thereto. At the lower. end of thispiston-rod is a cross-head B which is connected by rods C on each sideof the cylinder to cranks C on the main shaft one of which cranks onlyis represented.

N is the fly wheel.

In the -center of the head A I place an annular valve R, extendingaround the hollow piston rod B, and carrying a stuffing-box R withprojecting arms as represented, so that when the valve R is depressedthe passage is closed and an air tight chamber is formed below thepiston B; but when it is elevated, the passage is open and air isallowed to pass freely. The friction of the stufling-box, R, on thepiston-rod, B, tends to move the annular valve, R, in the same directionthat the piston B is traveling and to prevent any movement of R at anyother time or in any other direction. The arms or stops on R, bystriking A prevent the valve R from opening too wide.

An annular chamber, o", around the piston rod B, communicates with thevalve R, and also, by pipes r, communicates through the vfloor of theengine room with the external atmosphere. Another annular chamber, L,

exterior to 7", communicates with the interior of the cylinder A throughself acting valves H, H, which latter valves open outward from cylinderA. This chamber, L, also communicates through the tube E`with theheater, D, as represented. This heater may be made in a tubular,annular, or other suitable form, and serves thev ordinary purpose ofexpanding the air delivered thereto by the engine. The top of the heaterI) communicates with the top of the cylinder A by means of the pipe Fand valve F which valve receives motion from the main shaft, so thatitis opened when the piston B is at the highest point and is closed at aproper period during its ascent, to allow the air to act expansively.Other suitable mechanism may be employed in lieu of e and e with thesame effect.

M is the exhaust valve fitted in the head A of the cylinder, and is alsoactuated by ordinary means to open when the piston B is at its lowestpoint and to close a little before it has reached its highest point.

The operation of my invention is as follows: As the piston B rises bythe momentum of the fly wheel, the induction Valve R is raised from itsseat by the friction of the stufling box R and cool air flows in throughpipes r and chamber r, into the space under the piston B while the airabove the piston is blown out at the valve M. IVhen B arrives at the endof its up stroke, the valve F is opened by the cam e, and a measure ofcompressed and hot air from the heater D is admitted which by itspressure forces down the piston and actuates the engine. As the pistondescends the valve R is shut by the motion of the piston-rod and thecold air beneath the piston is compressed until its pressure equals andslightly exceeds the pressure within the heater, when it passes throughthe valves H, chamber h and pipe E into the heater. The valve F' is setso as to close when the piston has made about one quarter of its stroke,and the remainder is completed by expansion. I prefer to make the pistonrod B of such size that the pump side of the piston is about one halfthe area of the working side, though any other proportion may beemployed. If, now, the air in the heater D is doubled in volume by theaddition of heat, the pipe, E, will deliver a volume of air one half asgreat as is used in the working end of the cylinder, but if the air isexpanded less the pressure is reduced,

and the pipe E delivers a greater volume, the reverse taking place ifthe heat is increased.

In the operating of air or gas engines more or less difficulty hasalways been experienced from the accumulation of heat in the workingparts. In order to remove caloric and keep the parts cool, water or airhas been caused to circulate in contact with the surfaces of thecylinder'and in some cases water has been introduced to fill the piston.The use of water is objectionable in most cases and impracticable inmany, and in the use of air for such purpose no adequate means havehitherto been provided to move the air with rapidity. In my engine I useair for this purpose and have invented the follow ing means of applyingit: The piston B and piston rod B are made hollow and a solid plunger,O, is so placed that at each stroke of the piston a portion of the airwithin it is expelled and made to pass through a narrow annular spacebetween the piston rod and plunger, conveying away a portion of the heatfrom the metal of the piston and rod. At the up-stroke a fresh quantityof cool air is taken in to the piston through the same opening, to beagain expelled; thereby keeping up a constant circulation in closecontact with the surfaces which it is desired to keep cool. I alsoattach a vessel, P, to the piston rod, B, which vessel extends up aroundthe exterior of the cylinder A without touching it, leaving a thinannular space, x, between it and the cylinder. At each stroke of thepiston a quantity of air is alternately inducted and expelled throughthis opening and conveys away the heat which is transmitted downwardfrom the working end, and also that which might accumulate from thecompression of air in the pumping end. The pipes r and E pass throughopenings in the bottom of this vessel which are of sufficient size toallow P to play up and down upon them. By these means I am enabled tokeep the working parts of my engine sufficiently cool by the use of airalone and dispense with the use of water, and all the inconveniencesaccompanying it.

To the several features of my invention herein described, are due thefollowing several advantages: First, by the compressing and working ofthe air in the single cylinder A, by the use of the single piston B, andthe other parts arranged as represented I am enabled to construct myengine more simply, cheaply, and compactly. Second, by the peculiarconstruction and operation of the induction valve, R, and stufling box,R', I am enabled to open a'large passage for the induction of the air ata very early period in the up stroke of B, and to so control the motionof the valve R by the friction of R', upon the piston rod B', as toclose the opening without noise. Third, by the circulation of the airaround the plunger O, within the piston rod B, I spread the current overthe surfaces and remove the heat from the interior more effeotually andconveniently than has heretofore been practiced. Fourth, by theinduction and eduction of the air through the annular space around thecylinder, in the manner here shown, the cylinder is effectually andconveniently cooled and the working parts kept at a proper temperature.

Having now fully described my improved air engine, what I claim as newtherein, and desire to secure by Letters Patent is:

l. Compressing and working the air in the single cylinder, A, by thesingle piston, B, in combination with the valves and air passages R, 7",E, F, F, and M, or their equivalents, arranged and operatingsubstantially in the manner above specied.

2. The combination of the induction valve R with the stufIing-box R,piston rod B, and head A of the cylinder A, so that the friction ofl thestuiing box upon the piston rod, aids and controls the motion of thevalve, substantially as herein shown and described.

3. Causing a circulation of air through an annular space between theplunger :O and the interior of the piston or piston rod, for the purposeof cooling the latter, substantially as above set forth. n

4. Cooling the exterior of the cylinder A, by alternately inducting andexpelling air through an annular space X substantially in the mannerherein described.

O. M. STILLMAN.

Vitnesses:

DAVID SMITH, WILLIAM P. COY.

